The present invention relates generally to anti-plant pathogen materials and methods of use, and ore particularly, to anti-plant virus compositions and methods for their use.
Plant fungal and viral disease losses worldwide have been estimated to be as high as sixty billion dollars per year. Examples of plant viruses that contribute to significant losses in crop productivity are cucumber mosaic virus, tobacco mosaic virus and zucchini mosaic virus. The economic importance and control of plant viruses is discussed in Matthews, Plant Viruses, Chapter 16, Academic Press, Inc., San Diego (1991).
Considerable effort has been expended by the agricultural industry and by academic researchers in developing materials and methods for inhibiting infection by and/or reducing deleterious effects of plant pathogens. Kopp et al., Plant Physiol., 90, 208-216 (1989) describe a glucan preparation obtained from a fungus which serves as an inducer of resistance in tobacco to viruses (tobacco mosaic virus, tomato black ring virus and alfalfa mosaic virus) from three taxonomic groups. Pearce et al., Science, 253, 895-898 (1991) describe a native peptide, "systemin," that stimulates production of proteinase inhibitors (defensive proteins made in plants in response to wounding, for example, by insects) in tomatoes. Patent Cooperation Treaty (PCT) published application number WO 91/18984 describes methods for identifying and purifying plant proteins with anti-pathogenic (and particularly anti-fungal) activity.
Criteria determining the potential success of an anti-pathogenic composition in preventing or controlling plant diseases, especially viral diseases, include: whether the composition damages the plant; whether the composition affords systemic protection to the plant; whether the composition retains its activity for a reasonable length of time; whether the composition may be produced on a large scale at an economic price; and whether the composition would pass, or not be subject to, food and drug environmental protection regulations. So far there have been no commercially available antiviral chemicals that satisfy the foregoing criteria and there thus continues to exist a need in the art for new anti-plant pathogen compositions.